question stringlengths 37 38.8k | group_id int64 0 74.5k |
|---|---|
<p>I am working on analyzing a dataset that involves repeated measures data. The data was previously analyzed by a colleague using custom code written in C++, but I have expanded the dataset and am trying to analyze it in SPSS in a similar way. The dataset has a subjects variable that I want to specify as a random-effe... | 72,852 |
<p><strong>I am trying to create the algorithm that will tell me the good price to buy stuff and a correct re-selling price based on eBay item history.</strong></p>
<p>The main variables would be the auction type (buy now or bidding), price, if the item was sold and some sort of margin that has to be made on each tran... | 34,947 |
<p>I have read the comments about inferential statistics on census data. I am doing PhD and also facing the same problem with a little difference. </p>
<p>I have collected census data from the population of deans, directors,chairpersons and head of departments because of lack of availability on their part and can ge... | 34,949 |
<p>Is it true that if you want to make a CI for individuals: S(E)=S(x) and for groups S(E)=S(x)*sqrt(1-rtt)? Thanks in advance! </p> | 72,853 |
<p>I'd like to estimate the correlation between:</p>
<p>An ordinal variable: subjects are asked to rate their preference for 6 types of fruit on a 1-5 scale (ranging from very disgusting to very tasty) On average subjects use only 3 points of the scale.</p>
<p>A continuous variable: the same subjects are asked to qui... | 72,854 |
<p>I want to write an application, where users will have to choose between different "configurations", and I am looking for a way to statistically validate the "balance" of those "configurations", to make the equally "attractive" to users. Ideally, I'd like to use a Java API, as it would make it easy to "round-trip" (t... | 34,952 |
<p>I have two time series, $y$ and $x$, where
$y$ is sampled monthly and $x$ is sampled daily. I plan to use a mixed frequency regression(MIDAS) where I assign custom weights to the daily data points in $x$, and by doing so averaging it to $y$'s frequency. </p>
<p>My proposed model is as follows:</p>
<p>$y = \beta_y ... | 72,855 |
<p>In measuring the performance of a model, I divide my data into 2 sets, the training set and the test set, fit my model to the training set and then try to predict the results of the test set. If I'm looking at binary classification, I expect to classify my results into 0's and 1's. However, the output of the logisti... | 72,856 |
<p>The <a href="http://www.itl.nist.gov/div898/handbook/pri/section3/pri3361.htm" rel="nofollow">central composite design</a> method involves evaluating the experiment at the central point several times (typically 4 times). If this method was used for a deterministic computational experiment, then all center point resu... | 72,857 |
<p>I want to test mean differences between 4(0,1,2,3) groups for 6 different cell-types. In other words, I would have 6 comparisons to do for each cell-type (0-1,0-2,0-3,1-2,1-3,2-3). I have run a repeated-measures ANOVA before but it only gives me the main effects and interactions. To correct my t-tests for multiple c... | 49,909 |
<p><strong>Edited:</strong></p>
<p>I have a categorical variable comprising of values from 1 to 7 with these probability:</p>
<pre><code>score 1 2 3 4 5 6 7
p 0.01 0.01 0.03 0.05 0.2 0.3 0.4
</code></pre>
<p>In two different samples from the two different popul... | 72,858 |
<p>I was wondering if anyone knew if there exists built-in Matlab code for the above mentioned model? Here is the single-variate case:
<a href="http://www.mathworks.com/help/nnet/ref/timedelaynet.html" rel="nofollow">http://www.mathworks.com/help/nnet/ref/timedelaynet.html</a></p>
<p>I tried inputting my data into <co... | 34,958 |
<p>I have a problem when computing the mutual information between two variables.
Let's consider the following table:</p>
<pre><code> k=1 k=2 k=3
c = 1 10 20 5
c = 2 5 3 20
</code></pre>
<p>I want to calculate the mutual information between... | 49,843 |
<p>If </p>
<p>$$P = [0,0.9,0,0.1]$$</p>
<p>$$Q = [0,1,0,0]$$</p>
<p>Then $$KL(P||Q) = 0 + \ln(0.9/1)\cdot0.9 + 0 + 0 = -0.094$$ </p>
<p>This shouldn't be possible from the Gibbs inequality. What am I misunderstanding? </p> | 72,859 |
<p>What is the exact meaning of the subscript notation $\mathbb{E}_X[f(X)]$ in conditional expectations in the framework of measure theory ? These subscripts do not appear in the definition of conditional expectation, but we may see for example in <a href="http://en.wikipedia.org/wiki/Law_of_total_expectation" rel="nof... | 34,963 |
<p>I was reading a paper related to Auto encoders for my project work. It is required to input images as vectors to the neural network. I couldn't understand a certain sentence due to lack of knowledge of statistics (I guess). I Googled, but the problem is I don't know what it is exactly and searching the same phrase r... | 72,860 |
<p>I need to be able to find outliers in my data. I thought it best to test for this using the Kolmogorov-Smirnov Test. </p>
<p>I have over 800,000 points so I wanted a way to filter the data first to only test those that are on the edge of my sample. By eye I can fit an exponential decay (red line) but I was wonderin... | 72,861 |
<p>I'm using MathNet.Numerics library in C# to find the SVD but the Sigma matrix gives no indication of which values correspond to which features. It simply lists them in the most significant order.</p>
<p>I've heard that there is a way to do this in R, but I'm wondering if there is a way using C# to find which featur... | 72,862 |
<p>I have this question: </p>
<blockquote>
<p>It is reported that 45% of the population prefer apples and 55% prefer oranges. Describe the methodology for conducting the survey. </p>
</blockquote>
<p>I am not sure if my reasoning is correct:</p>
<p>Assuming the population prefers either apples or oranges (not both... | 72,863 |
<p>I'm not sure how to give context to this question. We're to use Excel to analyze data and use log base 10 for each column of data that we analyze, which I'm not sure what they want here. Are they wanting us to use the log base 10 for the analyzed data or for the raw data? Then the assignment asks us to determine if ... | 72,864 |
<p>We have the years from 2001, 2002, 2003,... to 2010. Say, a year is chosen at random from the listed years. What is the probability that the chosen year has 53 Mondays ?</p> | 72,865 |
<p>I have used R to form a 95% prediction interval for the number of endemic species on an island.<br>
My lower bound is negative – is that mathematically sound?</p>
<p>In the linear model used in the prediction interval, the data used are:
Area Surface area of island, hectares DiscSC Distance from Santa Cruz, kilome... | 72,866 |
<p>I am using methylKit to perform an analysis on my MethylCAP-bisulfite data.
The <code>prcomp()</code> function has been used in "PCASamples" (a command in methylKit)
to do PCA analysis on the data and I have a question about this:</p>
<p>The variable loading matrix has been stored in the <code>$rotation</code>, but... | 72,867 |
<p>This question is based on Honglak Lee's paper "Convolutional Deep Belief Networks for Scalable Unsupervised Learning of Hierarchical Representations". </p>
<p>I have implemented a convolutional RBM with probabilistic max-pooling based on equations in section 3.3. I now want to stack several of them as a convolution... | 72,868 |
<p>In a sequential (on-line) tree algorithm, I'm trying to estimate class label densities using a histogram. The algorithm grows a tree by generating test functions at each decision node, which correspond to the features in the data set. That is to say each feature is used to create a test in the form of $g(x) > 0$ ... | 10,417 |
<p>I have 2 text files containing certain sentences. I calculated the individual probabilities of every single word in both files. </p>
<p>for file1:</p>
<p>$$p(\text{A})=\frac{(\text{total occurrence of a word in file 1})}{(\text{total no of words in file 1})}$$</p>
<p>for file2:</p>
<p>$$p(\text{B})=\frac{(\text... | 72,869 |
<p>I'm working on an empirical analysis where I try to predict stock returns using weekly data. Ideally, I would like to use a panel data model like the following:
$$
Y_{it}=X_{it}'\beta+\varepsilon_{it}
$$</p>
<p>(here presented in a very simple format - it will be more complex in the analysis)</p>
<p>Here $Y_{it}$... | 34,974 |
<p>What is the number of nodes in an unpruned decision tree that is trained using n samples and that grows until there is only one sample in each leaf?</p>
<p>I would like to know if there is a formula to compute it or at least some way to define a lower bound. </p>
<p>If each node splits the number of samples in ha... | 72,870 |
<p>I am very new to statistics, and have searched around the net and stack exchange for an answer without luck. Therefore this post. I hope someone can help...</p>
<p>I am carrying out an analysis of the environmental impact of about 100 parametrically generated external wall constructions. For each variant, I have re... | 72,871 |
<p>Let $R_{it}$ and $R_{mt}$ be daily stock returns for some company $i$ and the daily market index returns (respectively), with $i \in \{1,...,N\}$ and $t \in \{1,...,200\}$. It is common to have $R_{it}$ as the response and $R_{mt}$ as the predictor. </p>
<p>Let a severe financial crisis occur at $t=150$ and this cr... | 72,872 |
<p>How do I find the adjusted $R^2$ (or $r^2$) from Lasso and Ridge regression?</p>
<p>I used the glmnet package. For instance if I have this code so far....</p>
<pre><code>###LASSO
library(glmnet)
attach(mtcars)
y=mtcars$mpg
model=model.matrix(mpg~ . data=mtcars)
lasso.reg=cv.glmnet(model, y, type.measure=... | 34,976 |
<p>I am currently experimenting with on-line symbol recognition for mathematics for my bachelors thesis. I have 369 symbols which I would like to distinguish.</p>
<p>There are a lot of preprocessing methods / features which I could think of being useful, but I am not too sure about which are good / bad or which combin... | 72,873 |
<p>I've been google-ing around but couldn't find an answer to my question. Any help would be appreciated.</p>
<p>The simplest example of my problem is: Imagine I have an bag of marbles of many different colors. Someone comes along and takes a 'possibly' random sampling of X marbles. Someone comes along later and draws... | 72,874 |
<p>I have some survey data, where the first question is something like, "rate how you are feeling on a scale of 1 - 5". The next group of questions are something like, "do you smoke?" or "how much exercise do you get per day: 0, 15, 30, 45, 60, 60+?"</p>
<p>I'm looking for a way to visualize this data, where each qu... | 46,264 |
<p>I am a pure math grad student with little background in applied mathematics. Since last fall I have been taking classes on Casella & Berger's book, and I have finished hundreds (230+) of pages of exercise problems in the book. Right now I am at Chapter 10. </p>
<p>However, since I have not majored in statistic... | 34,983 |
<p>If one is using gradient descent to optimize over a vector space where each of the components is of a different magnitude, I know we can use a preconditioning matrix $P$ so that the update step becomes:</p>
<p>$$x_{n+1} = x_n -\gamma_n P^{-1}\ \nabla F(x_n)$$</p>
<p>The obvious approach for $P$ is to make it a dia... | 34,984 |
<p>I read a Q/A from <a href="http://stats.stackexchange.com/questions/8309/how-to-calculate-regularization-parameter-in-ridge-regression-given-degrees-of-f">here</a> which is extremely nice.</p>
<p>In the above Q/Answer the tuning parameter $λ$ was a scalar. But in my problem it is a vector $\lambda$ for a generalize... | 72,875 |
<p>If I have a dataset with a very rare positive class, and I down-sample the negative class, then perform a logistic regression, do I need to adjust the regression coefficients to reflect the fact that I changed the prevalence of the positive class?</p>
<p>For example, let's say I have a dataset with 4 variables: Y, ... | 72,876 |
<p>So lets say I have N items and I want to rate their relevance (say on a 5-point likert scale: 1 being least and 5 being most relevant) to the "perception of beauty" and I have M number of participants to do the ratings.
Since N items are too much for one participant to rate, I split my M participants to 4 groups a... | 34,987 |
<p>Hopefully somebody will be able to shed some light on my SPSS problems! </p>
<p>I have been given 65 values. 57 of these data values are quarterly results and 8 are the holdback data to be used. </p>
<p>I have to do:
- Regression with Dummy variables with a linear trend cycle component </p>
<p>Does anyone know w... | 72,877 |
<p>Is it possible to extract data points from moving average data?</p>
<p>In other words, if a set of data only has simple moving averages of the previous 30 points, is it possible to extract the original data points?</p>
<p>If so, how?</p> | 34,990 |
<p>I have around 50 dependent quantities (regressor variables).</p>
<p>I want to find the best relation between the response variable data and regressor variable data. </p>
<p>I tried multiple linear regression with 3 combinations but could not get correlation coefficient between original and predicted y variable gre... | 72,878 |
<p>Let $X$, $U$, $V$, $W$, $Y$ be independent exponential random variables with respective means
$\frac{1}{6}, \frac{1}{4}, \frac{1}{3}, 1, \frac{2}{3}$. Use the variables $X, U, V, W, Y$ to construct a variable having an $F$ distribution with $(3,2)$ degrees of freedom.</p>
<p>The issue here is that no matter what I ... | 72,879 |
<p>I'm calculating the confidence intervals around an estimate using bootstrapping techniques. I'm particularly fond of the percentile method, given its simplicity and general intuitive nature. However, I'm also interested in applying the finite population correction factor ($fpc$) to adjust the lower and upper bound... | 72,880 |
<p>I am an analyst on a paper and, in writing up methods and results, noted that one of the proposed (logistic regression) models did not converge due to separation. I noted this in the <em>results</em> section of the paper, but the authors have asked that this be moved to the <em>methods</em> section. </p>
<p>It does... | 72,881 |
<p>I'm just trying to implement a simple discrete Hopfield net using Matlab but there is a problem with my result. As I present two patterns to be stored in my net everything works great and I can retrieve the correct association pattern given a noisy input, but if I just decide to store or train more than 2 patterns t... | 34,995 |
<p>I'd like to have some control lines that converge, if the random variable observed becomes stable.</p>
<p>For example, as the chart below, the variable starts at around 3.0, the upper control line is around 6.0, and lower control line is about 2.0. </p>
<p>At the beginning there's less data so the uncertainty is h... | 72,882 |
<p>I have a study looking at classroom socialization. Students named the top other students they wanted to read a book with before and after treatment. There was also a control group that received no treatment. Before the treatment you have a few really popular kids getting all the votes and a lot dorkier kids getti... | 72,883 |
<p>Let's say I have two signals $x$ and $y$, sampled $N$ times, i.e.</p>
<p>$$ x = [ x_{1}, x_{2}, ..., x_{N} ] $$
$$ y = [ y_{1}, y_{2}, ..., y_{N} ] $$</p>
<p>I would like to check whether $x$ and $y$ are statistically independent, with a certain level of probability.</p>
<p>I have been looking into the <a href="... | 34,998 |
<p>Based solely on the temporal pattern of mouse clicks (a list of click times $[t_1,t_2,t_3,\ldots]$), is it possible to predict the computer user's activity?</p>
<p>For example out of: working vs spending time on Facebook vs watching photos vs playing a computer game.</p>
<p>If they are any more fine-grained predic... | 46,277 |
<p>I am working on reducing the data from a particular type of particle detector. When struck by a particle, this detector produces a voltage pulse that has the form of a Gaussian convolved with an exponential decay.</p>
<p>Among the earlier work done with this sort of detector, I've found one journal article which su... | 46,278 |
<p>In a large sample ($N = 3,265,506$ for my study) tests are always significant. Is there an article in the literature I can cite to justify using effect size instead of significance testing?</p> | 47,622 |
<p>Can anyone explain to me advantages and disadvantages of classification SVM that distinguishes it from other classifiers?</p> | 46,279 |
<p>I have some data about two machines, each machine has 10-15 operation logs, and inside the log are the time-stamped status checks that takes on the value of <code>1</code> if there is a warning and <code>0</code> otherwise.</p>
<p>The question is to decide which machine is better? (in terms of less warnings in the ... | 46,280 |
<p>What methods are there to fit a model of the form $y=A\mathrm e^{Bx}+C\mathrm e^{Dx}+E$? </p>
<p>Here is the actual scientific data to be fitted: <a href="http://dl.dropbox.com/u/39499990/Ben%2C%20real%20data.xlsx" rel="nofollow">http://dl.dropbox.com/u/39499990/Ben%2C%20real%20data.xlsx</a></p>
<p>B should be in ... | 42,549 |
<p>I want to implement snowball sampling using web-based software. Basically, at the end of the survey, the consumer can choose to provide me some names and emails of other respondents. I would like the software to automatically email out the link to the survey with appropriate text (e.g. Your name was provided by resp... | 72,884 |
<p>This may be well known, but I don't know the literature well. I've also tried to do the integral myself, but it's beyond my abilities</p>
<p>The situation: I have two independent random variables $Y_1$ and $Y_2$. These variables are normally distributed $Y_i \sim N(\mu_i,V_i)$. The sum is also normally distri... | 46,282 |
<p>I just attempted implementations of Ward linkage and <a href="http://en.wikipedia.org/wiki/UPGMA" rel="nofollow">UPGMA</a> linkage, as well as Pearson and Euclid similarity coefficients. To my surprise, both similarity coefficients gave the same clustering with the Ward linkage. Should this be the case? Is this a... | 72,885 |
<p>I'm modeling growth curve of several ecosystems with respect to their rainfall-productivity relationship using a simple linear regression </p>
<p>$\text{ANPP}(t)=a+b\cdot\text{Rain}(t)$ </p>
<p>and a modified version of the Brody Model </p>
<p>$\text{ANPP}(t)=a\cdot\left[1-e^{(-b\cdot\text{Rain}(t))}\right]$,</p>... | 72,886 |
<p>I'm new to Empirical Likelihood Estimation. </p>
<p>I'm trying to find an example of how to find the empirical likelihood estimate of a univariate mean $\mu$ using the <code>emplik</code> software package in <code>R</code>. </p>
<p>Any help or reference is greatly appreciated.</p> | 35,006 |
<p>This is my first post so forgive me if this is question has already been asked. I searched around the forum but didn't find anything specific to what I'm looking at currently.</p>
<p>I'll keep things as simple as possible --- (to allay the potential annoyance of semantic sticklers, when I say "the effect is signifi... | 35,007 |
<p>I have a three dimensional table of size $6\times6\times81$. Each cell of the table is a hypothesis test. Slicing the table on the third dimension produces $81$ sets of hypothesis tests which are independent between sets but dependent within sets. Originally I was thinking that I could just control the false discove... | 72,887 |
<p>I work for an organization that oversees around 180 schools across the country. We regularly collect outcome data from these schools and rank them. I have been asked to do a survey of the national office (around 100 people) to determine what the best and worst <em>perceived</em> schools are, based on the staff's n... | 72,888 |
<p>In a city of 2 millions people, with 950km of streets, I'd like to estimate the probability to get close to a smoker i.e. less than 10 meter.</p>
<p>For that let's represent streets without width, in a single line</p>
<p>Each day (14 working hours) 2 millions cigarettes are smoked in the streets, let's suppose smo... | 72,889 |
<p>Let Qn = Cqn.{|Xi-Xj|;i < j}_(k) so for a very short sample like {1,3,6,2,7,5} it can be calculated from finding the kth static order of pairwise differences: </p>
<p><strong>7 6 5 3 2 1</strong></p>
<p><strong>1</strong> 6 5 4 2 1</p>
<p><strong>2</strong> 5 4 3 1</p>
<p><strong>3</strong> 4 3 2</p>
<p><st... | 46,300 |
<p>I am running a logistic model. The actual model dataset has more than 100 variables but I am choosing a test data set in which there are around 25 variables. Before that I also made a dataset which had 8-9 variables. I am being told that AIC and SC values can be used to compare the model. I observed that the model h... | 72,890 |
<p>I am running Cointegration and VECM on a set of endogenous and exogenous variables. Do I have to run unit root tests on the exogenous variables and make sure they are I(1)?
Thanks a lot.</p> | 72,891 |
<p>I have some data corresponding to changes in a binomial variable - i.e, in month 1 there were n1 trials and k1 successes, and in month 2 there were n2 trials and k2 successes. Say I have M of these cases, and in between month 1 and month 2 there were performed a number of different operations (so for case 1 we migh... | 72,892 |
<p>An example of linear regression could look like:</p>
<p>$min \sum_{i=0}^{m}||x_i A - y_i||_2^{2}$, where ${x_i, y_i} \in \mathbb{R}^n$ and $A \in \mathbb{R}^{n\times n}$.</p>
<p>I am interested in knowing how do I solve such problem with an of the following extra constraints, $A$ is an orthogonal matrix or $A$ is ... | 72,893 |
<pre><code>var w = 810,
h = 400,
mapMargin = 30;
geo = pv.Geo.scale().range(w, h);
var vis = new pv.Panel()
.width(w)
.height(h)
.top(50)
.bottom(30)
.def("i", -1);
var dot = vis.add(pv.Dot)
.data(geoPopList)
.left(function(d) {return geo(d.center).x})
.top(function(d) {retur... | 46,307 |
<p>I have developed a scoring system using logistic regression. The score ranges between 0 and 6 (using integers) and predicts death. It does not use a conventional regression formula and thus I am not able to calculate a precise value of the predicted risk of dying. An example of the score could look like this:</p>
<... | 35,020 |
<p>I want to tell something about predictability of health improvement results after a specific surgical procedure. I asume that the smaller the SD around the mean, the more predictable the results are.
If I want to compare two subgroups, for example males and females, I find two different means and also two different ... | 35,022 |
<p>We know that the least square method is equivalent to the MLE for Gaussian distributed errors. What is the relationship (if any) between regularized (Tichonov regularization) least squares and MLE?</p> | 72,894 |
<p>I have a 12-level factor variable (month) in my dataset and I wanted to fit a CART tree with rpart(). Would you split the 12-level factor variable into 12 dummy variables?</p>
<p>If I fit the model with one 12 level factor variable I get better predictions (in comparison to the 12 dummy-variable alternative) but th... | 72,895 |
<p>Consider the infinite order MA process defined by
$$y_t=\epsilon_t+a(\epsilon_{t-1}+\epsilon_{t-2}+...),$$
where $a$ is a constant and the $\epsilon_t$s are i.i.d. $N(0,v)$ random variable.</p>
<p>What is the best way to show that $y_t$ is nonstationary? I know that I need to look at the characteristic roots of th... | 72,896 |
<p>Is it possible to do model selection in this way? Suppose I need to select a good (logistic) model among three variables (var1, var2, var3). The deviance D* (-2*log-likelihood) of this full model would be the minimum among all possible models. Then I could try all 6 combination of sub-models(1,2,3,12,13,23) and comp... | 72,897 |
<p>CrossValidated Community,</p>
<p>I must mention that I am a first-time poster (and relatively new to both modelling and R), so please excuse any norms I may violate in my post and politely inform me.</p>
<p>I have been attempting to determine if a treatment variable is significant in R and to find a package that w... | 72,898 |
<p>I'm teaching myself MCMC methods and I encountered this passage in a book that I am not able to make head or tails of:</p>
<blockquote>
<p>The phenomenon of pseudo-convergence has led many people to the idea of comparing
multiple runs of the sampler started at different points. If the multiple runs appear to
... | 72,899 |
<p>Would it be possible to approximate accurately the relative quantities of <a href="http://en.wikipedia.org/wiki/Loonie" rel="nofollow">Loonies</a>, <a href="http://en.wikipedia.org/wiki/Toonie" rel="nofollow">Twoonies</a>, quarters, dimes, nickles (and perhaps the discontinued penny) in circulation from simply obtai... | 72,900 |
<p>Suppose I have a set of stimulus, that was rated by three independent rater.
I then estimated the Intraclass correlation coefficient, with a resulting value of 0.881.
Let's consider a practical example: three neuroradiologists estimated the hippocampal thickness of 50 different subjects.</p>
<p>What is the correct ... | 72,901 |
<p>The degrees of freedom in a multiple regression equals N−k−1, where k is the number of variables.
Does k include dummy variables? </p>
<p>For example, I have the model:
Y=B1+B2D2+B3D3+B4D4+B5X1+B6X2+B7(D2D3)+B9(D2D4)+B9(D3D4)+B10(D2D3D4)+u
(there are 2 X variables and 3 dummies)</p>
<p>N=14780
To get the Degrees o... | 23,072 |
<p>The Binomial distribution models the number of successes in N trials, but the successes can be in any order. What's the distribution for when the successes have to be in a specific order? Do you just drop the binomial coefficient?</p> | 72,902 |
<p>I know that HMMs can be used to construct statistical models of text. Thus, we can generate text according to this model, and compute the likelihood of a text sample under the model.</p>
<p>What tools are used to construct statistical models of websites or webpages? Basically, it means things like various paragraph... | 46,319 |
<p>I am trying to evaluate model performance (regression problem). In literature, some use RMSe and others use correlation. </p>
<p>Is there any difference between both the approaches?
Here: <a href="http://stats.stackexchange.com/questions/56302/what-are-good-rmse-values">What are good RMSE values?</a>
I saw that RM... | 72,903 |
<p>(first of all I simplified my question) </p>
<p>depending on the input info below, I want to create proper excel function in output part.</p>
<p>what I require verbally in output part under "<em>status (0 or 1) column</em>" is</p>
<p>depending on the value of "<em>accumulated age</em>", generate 0 (zero) with cor... | 698 |
<blockquote>
<p>You test a classifier on a test set consisting of 10 iid items. The classifier makes 2 mistakes. Assume the true error rate is $x$.</p>
<p>Let the prior be $ x \sim Beta(\alpha, \beta)$. Derive the posterior given the classifier's performance. </p>
</blockquote>
<p>I know that to calculate the p... | 72,904 |
<p>Consider an epidemic curve like the one below, or any other count-based time series data:</p>
<p><img src="http://i.stack.imgur.com/G0qML.png" alt="enter image description here"></p>
<p>If, as it turns out from digging into the records, retrospective data collection, or just a series of case reports that got sent ... | 72,905 |
<p>I am evaluating a multi class classifier. As precision and recall are only defined for binary classification I want to create precision recall curves for every class by separating one class from all other classes. Using one-vs-all SVMs it’s very simple. For each class the appropriate SVM delivers a score which can b... | 72,906 |
<p><a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1474-919X.2012.01265.x/full" rel="nofollow">Table 3 of this paper</a> uses the letters A, B and C to show statistically significant differences between variables. I cannot understand what the letters A, B and C actually mean however. Can anyone explain which vari... | 72,907 |
<p>Let's assume a probability mass function $P$ on the discrete domain $\{0,...,N\}$ and a density function $f$ and the existence of two real factors $a$ and $b$ so that we have for all numbers $k$ in $\{0,...,N\}$:</p>
<p>$$P(k) = a * f(k * b)$$</p>
<p>What can be said about the theoretical / mathematical relationsh... | 35,036 |
<p>I have two classes and, in total, 40 subjects <code>(20,20)</code>. I used an SVM to implement classification and did a leave-one-out cross validation to get an overall performance of the classifier. </p>
<p>How could I draw an ROC curve for this situation? </p>
<p>Is it even necessary to draw a ROC curve in this ... | 46,324 |
<p>I'm trying to fit a model under JAGS where I have a response, y, that depends linearly on eight predictors (with no intersect : I'm actually trying to evaluate the share of each socioeconomic statuts population that voted for a candidate, wth aggregated data). </p>
<p>My problem is that naive hierarchical modelling... | 72,908 |
<p>In the attached images (bottom of this post), I wish to compare the plotted distributions as follows. Each plot shows two distributions labelled 'Forwards' and 'Backwards'. For each attached example, I wish to compare each of 'Forwards' and 'Backwards' of sub-figure a with 'Forwards' and 'Backwards' of sub-figure c ... | 72,909 |
<p>We'd like to express how much better A performs when combined with B. Is it as simple as comparing the averages of the two groups?</p>
<p>When tested, widget A has a range of results from 36 to 43 with an AVG of 40(x).
When widget B is tested together with product A, the results have a range of 27 to 34 and an aver... | 35,038 |
<p>Let's say I'm analyzing the mean number of students per class for a school district. The district has imposed a hard limit on the maximum ratio: there can never be more than 30 students in a class. The district strictly enforces this rule and it is known to hold true.</p>
<p>I'd like to construct a confidence int... | 35,039 |
<p>This sounds like a problem that has to be well known, but I can't find a good answer. I have tried another forum before I realized there was a stackexchange stats site. So here goes...</p>
<p>I have two competing models for the fraction of special objects $n$ in a sample $N$. One model predicts that $f= \frac{n}{N}... | 46,327 |
<p>I have a data classification problem and I'm wondering what is the best machine learning approach to use for the particular constraints of my problem.</p>
<p>My constraints are as follows:
- the data points are not linearly separable (in the original space)
- I can generate as many training samples of either posi... | 39,072 |
<p>I need to understand how to read kernel density graphs. How do you come up with the values in y-axis?<img src="http://i.stack.imgur.com/8CRLT.jpg" alt="enter image description here"></p> | 49,910 |
<p>For the end-terms in a large public university (LPU), there were qualitative tests for 5 courses. Every one of the 1000 students took every test, so there are 5000 answer scripts. Every test was scored between 0 and 100, so each student could get an aggregate score between 0 and 500. The scripts were distributed o... | 72,910 |
<p>In a book I am reading, the author have calculated the Pearson $\chi^2$ statistic value as 11.50 and degree of freedom = 9. The p-value stated is 0.241. I look it up in a $\chi^2$ table but I only can see 4.168 (p=0.9) and 14.68 (p=0.1). So 11.50 lies somewhere in between (0.241). How does the author get 0.241. I th... | 72,911 |
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